Happy birthday, Princess Charlotte!

The British royal family on Sunday released four brand-new photographs of the princess, to mark her turning 1 on Monday.

The adorable pictures were taken by her mom, Catherine, Duchess of Cambridge, at Anmer Hall -- the family's 10-bedroom country house on Queen Elizabeth II 's Sandringham Estate in Norfolk, England.

In one of the shots posted to Twitter by Kensington Palace , the royal baby looks pensively into the distance with a bow in her hair: